Diazonium compounds and diazotype materials containing them



United States Patent 3.442.651 DIAZONIUM COMPOUNDS AND DIAZOTYPE MATERIALS CONTAINING THEM Andreas Joseph Johannes Hendrickx and Bernardus Hubertus Huibers, Venlo, Netherlands, assignors to Chemische Fabriek L. Van Der Grinten N.V., Venlo, Netherlands, a Dutch corporation No Drawing. Filed Mar. 10, 1966, Ser. No. 533,388 Claims priority, application Netherlands, Mar. 12, 1965,

Int. Cl. G03c N52 US. CI. 96-91 Claims ABSTRACT OF THE DISCLOSURE This invention relates to diazonium compounds of a new type and to diazotype material manufactured with the aid of these diazonium compounds. The diazotype material may be so-called one-component diazotype material which is developed with a liquid containing an azo-coupling component, so-called two-component diazotype material which is developed with the aid of ammonia vapor, or heat developable diazotype material.

Besides adequate light-sensitivity, suitable coupling activity, and reasonable stability, diazonium compounds for sensitizing diazotype material should, as a rule, have a number of other properties. A very important one of these is that the photo-decomposition should form products which are completely or almost completely colourless, which when exposed to light show little or no staining, and which do not actively react with diazonium compounds to yield dyestuffs.

If the photo-decomposition product is stained, copies made on the diazotype material also show a stained, completely exposed background. This is especially disadvantageous when the support of the diazotype material is white paper or when the support is transparent and the copy is to serve as an intermediate for further copying on diazotype material. Another disadvantage arising when the photo-decomposition product has the property of staining when exposed to light is the yellowing which the copies will show with age. When the photo-decomposition product has the property of actively reacting (e.g. coupling) with diazonium compounds to form dyestuffs, in those areas of the diazotype material in which the diazonium compound has not completely bleached out a mixture of dyestuffs is formed upon development. Because of the reaction of the photo-decomposition product, inconvenient colour dififerences, so-called off-shades, may appear in said areas, especially when the azocoupling component which is present in the material or is added to the material upon development produces a dark azo-dyestutf with the diazonium compound, which means that the shade of the foggy background of the copies does not correspond with the colour of the azodyestuif in the slightly exposed or non-exposed areas.

In recent years diazonium compounds of very high light-sensitivity have come into use for sensitizing diazotype materials. These compounds are chiefly benzene diazonium compounds having a tertiary amino group in the para-position with respect to the diazonium group and an etherified hydroxyl group in themeta-position, and possibly a further substituent such as alkoxy, alkyl, or halogen in the para-position with respect to the etherified hydroxyl group.

British patent specification No. 867,629 describes diazonium compounds of the general Formula I in which X is an anion, R representsan alkyl group, R represents an alkyl group, and R represents an alkyl or an aralkyl group.

British patent specification No. 867,630 describes diazonium compounds of the general Formula II azonium compounds of the general Formula III OR1 N in which X is an anion, Y is a hydrogen or halogen atom, or an alkyl or alkoxy group, R represents an alkyl group, R represents an alkyl group with at most 3 C-atoms, and R represents a cyclohexyl group.

Diazotype material sensitized with diazonium compounds according to the Formulae I, H and III has high light-sensitivity. It may be one-component diazotype material or two-component diazotype material. One-component diazotype material according to these patent specifications furnishes copies with brown azo-dyestulf images upon development withweakly alkaline phloroglucinol developers, andwhere the diazonium compound used has sufiicient coupling activity-upon development with the commonly used buttered weakly acid phloroglucinol developers yields copies with darker azo-dyestutf images, which in the diazotype process are even called black.

The completely exposed background of the copies, however, is somewhat stained.

Moreover, when exposed for a considerable time to daylight or to light of high-pressure mercury vapour lamps, which are commonly used as copying light-source in the diazotype process, the copies show a not-negligible yellowing, which has an unfavourable influence on the whiteness or the clearness of the white copies as well as on the light-transmission of the transparent copies.

The diazonium compounds according to Formulae II and III in which Y is a halogen atom have a higher coupling activity than the compounds according to Formula I. Moreover, in aqueous solutions they have less tendency to precipitate with aryl sulfonic acids, particularly with naphthalene-1,3,6-trisulfonic acid, which is widely used as a stabilizer in the diazotype process, and their azo-dyestuffs are less sensitive to changes of pH which may occur at the surface of diazotype copies.

However, upon exposure to light they yield photo-decomposition products which are capable of forming dyestuffs with diazonium compounds. When copies made on diazotype materials sensitized with the said diazonium compounds according to Formulae II and III are developed with a buffered weakly acid phloroglucinol developer, in the areas in which the diazonium compound has not completely bleached out these photo-decomposition products participate so actively in the dyestutf formation that marked colour differences (off-shades) result in those areas.

The invention relates to diazonium compounds of a new type and to diazotype material manufactured with the aid of these compounds, which material avoids or minimizes the disadvantages described above with respect to the known materials.

According to the present invention there are provided diazonium compounds of general Formula IV in which X is an anion, Y is a halogen atom, R is a substituted or non-substituted alkyl, branched alkyl, unsaturated alkyl, cycloalkyl, or aralkyl group, R represents a substituted or non-substituted alkyl, branched alkyl, or aralkyl group, and R represents a substituted or nonsubstituted cycloalkyl or aralkyl group.

The diazonium compounds according to the invention are very light-sensitive and yield both light-coloured and dark azo-dyestuffs with the azo-coupling components commonly used in the diazotype process. They bleach out more clearly and they form less reactive photo-decomposition products than the diazonium compounds according to Formulae I, Hand III.

Diazotype materials sensitized with diazonium compounds according to the invention yield copies which have a clearer completely exposed background, show less yellowing, and in consequence of the low reactivity of the photo-decomposition product, particularly upon development with weakly acid buffered phloroglucinol developers, show fewer off-shades than corresponding diazotype material sensitized with a diazonium compound according to Formulae I, H, and III.

The following table provides a list, though not a complete one, of diazonium compounds which can be used with good results in diazotype material according to the invention Table 4-diazo-3-fluoro-2-methoxy-N-methyl-N-benzylaniline 4-diazo-3-chloro-2-methoxy-N-methyl-N-benzylaniline 4-diazo-3-chloro-2-butoxy-N-methyl-N-benzylaniline 4-diazo-3-chloro-2-methoxy-N-ethyl-N-(2',6'-dichlorobenzyl -aniline 4-diazo-3-chloro-2-ethoxy-N-(2'-hydroxyethy1)N-benzylaniline 4-diazo-3-chloro-Z-methoxy-N-Z-chloroethyl-N-benzylaniline 4-diazo-3-chloro-2methoxy-N-n-propyl-N-benzylaniline 4diazo-3-chloro-2-methoxy-N-isobutyl-N-benzylaniline 4-diazo-3-chloro-2- (2'-ethoxyethoxy -N-ethyl-N-benzylaniline 4-diazo-3-chloro-Z-methOXy-N-methyl-N- (naphthyl( 1) methyl)-aniline 4-diazo-3-chloro-2-methoxy-N-methyl-N-cyclohexylaniline 4-diazo-3-bromo-2-methoxy-N-methyl-N-cyclohexylaniline 4-diazo-3-iodo-2-methoxy-N-methyl-N-cyclohexylaniline 4-diazo-3-bromo-2-n-propoxy-N-methyl-N-cycl0hexylaniline 4-diazo-3-chloro-2-isobutoxy-N-methyl-N-cyclohexylaniline 4-diazo-3-chloro-2-methoxy-N-ethyl-N-cyclohexylaniline 44diazo-3-chloro-2-methoxy-N-methyl-N-(4--methylcyclohexyl)-aniline 4-diazo-3-chloro-2-allyloxy-N-methyl-N-cyclohexylaniline 4-diazo-3-chloro-2-cyclopentoxy-N-methyl-N-cyclohexylaniline 4-diazo-3-chloro-2-benzyloxy-N-methyl-N-cyclohexylaniline 4-diazo-3-chloro-2-methoxy-N,N-dibenzylaniline 4-diazo-3-chloro-2-methoxy-N-benzyl-N-cyclohexylaniline.

These diazonium compounds can be used as diazonium salts, e.g. as diazonium chloride, sulfate, or metal chloride double salt, such as chlorozincate, chloromanganate and chlorostannate, as diazonium borofluoride or diazonium aryl sulfonate.

They can be applied in diazotype material individually, mixed together, or in admixture with diazonium compounds of other types. It goes without saying that a diam type material according to the invention, accordingly as it contains a higher content of another diazonium compound, will present the specific advantages of the diazonium compounds according to the invention to a less degree.

With the diazonium compounds according to the invention the familiar supports such as paper, tracing paper, printing-plate paper, tracing linen, opaque linen, synthetic paper, metal sheets, glass fibre, polyester film and the like can be sensitized. The diazonium compound may or may not be incorporated in a hydrophilic or hydrophobic film layer.

Preferred diazonium compounds according to the invention are those carrying a chlorine or bromine atom in the orthoposition with respect to the diazonium group, an unbranched alkoxy group with at most 4 C-atoms in the meta-position with respect to the diazonium group, and a N-alkyl-N-cyclohexylamino group in which the N-alkyl group contains at most 3 C-atoms in the paraposition.

One-component diazotype material sensitized with these compounds, when developed with the conventional alkaline phloroglucinol developers, yields copies with particularly fine brown azo-dyestutf images, viz. images with the highly desirable sepia colour.

In the diazotype material according to the invention the conventional auxiliary. agents can be used, e.g. acids, such as citric acid, tartaric acid and boric acid; stabilizers, such as benzene and naphthalene sulfonic acids, p-phenolsulfonic acid, and their water-soluble salts; metal salts,

such as zinc chloride, magnesium chloride, nickel sulfate and alum; materials which serve to improve the developing speed, such as glycerol, polyethylene glycol, urea, thiosinamine and the like; surface-improving substances, such as finely divided silicon dioxide (colloidal or non-colloidal), aluminium oxide, barium sulfate and rice starch; binders, such as gelatin, gum arabic, cellulose ethers, starch derivatives, polyvinyl alcohol; dispersions of synthetic resins, such as dispersions of cationic, non-ionic, and anionic polyvinyl acetate; substances which serve to stabilize the background of the copies, such as thiourea.

The phloroglucinol developers which are used in the one-component diazotype process often vary as to their composition and acidity. Below, two weakly acid phloroglucinol developers and one weakly alkaline phloroglucinol developer are described which are employed in practice and are used for development in a number of the following examples.

Developer A is a solution of:

Phloroglucinol g 4 Acetoacetanilide g 0.1 2-ethylhexyl sulfate ml 3 Beet sugar g 15 Benzoic acid g 2.5 Sodium benzoate g 14 Sodium formate g 135 in 1000 ml. of water.

The pH of this liquid is approximately 5.8.

Developer B is a solution of:

Phloroglucinol 6.5 Resorcinol 4 Thiourea 10 Sodium dibutylnaphthalene sulfonate 2 Sodium formate 14 Sodium benzoate 22 Trisodium citrate (2 aq.) 49 Citric acid 1.2

in 1000 ml. of water.

The pH of this liquid is approximately 6.5.

Developer C is a solution of:

Thiourea 30 Phloroglucinol 5.4 Resorcinol 6.5 Potassium hydroquinone monosulfonate 1 Sorbitol 5 Beet sugar 15 Potassium tetraborate (5 aq.) 50 Sodium isopropylnaphthalene sulfonate 1.5 in 1000 ml. of water.

The pH of this liquid is approximately 9.5.

The following examples will serve to illustrate the invention:

EXAMPLE I (A) A sheet of white base paper for the diazotype process, of weight 80 g./m. is sensitized with a liquid containing 4-N-methyl-N-benzylamino 3-methoxy 2-chlorobenzene diazonium chloride, stannic chloride double salt g 27.3 Tartaric acid g 5 Aqueous polyvinyl acetate dispersion (Vinnapas H. 60 from Wacker-Chemie G.m.b.H., Munich,

Germany) ml 30 Water ml 1000 and dried.

(B) Another sheet of white base paper for the diazotype process, of weight 80 g./m. is sensitized with a liquid containing:

4-N-methyl-N-benzylamino 3-methoxy 6-chlorobenzene diazonium chloride, zinc chloride double salt g 23.7 Tartaric acid g 5 Aqueous polyvinyl acetate dispersion (Vinnapas H. 60) *ml 30 Water ml 1000 and dried.

The two diazotype papers are very light-sensitive. Diazotype paper A has a higher developing speed than diazotype paper B.

A strip of each sheet is imagewise exposed underneath a transparent ink drawing until the diazonium compound underneath the image-free portions of the drawing has completely bleached out. Both strips are then developed with developer C. Thus two copies with a brown image on a white background are obtained. The background of copy A is whiter than that of copy B. When both copies are placed in daylight or exposed to the light of a high-pressure mercury vapour lamp, it is found that copy B shows stronger yellowing than copy A.

A strip of each sheet is imagewise exposed underneath a drawing on tracing paper, in which drawing some black areas drawn in India ink are present, until the' diazonium compound underneath the image-free portions of the drawing has largely bleached out. The strips are developed with developer B. Both copies show a black image on a foggy background. The background of copy A is grey; the background of copy B is not grey but reddish brown, which is due to the reactivity of the photo-decomposition product of the diazonium compound.

The diazonium compound according to the invention used in this example was prepared as follows:

2,3-dichl0ronitr0benzene was converted with sodium methanolate into 3-chloro-2-methoxynitrobenzene. The nitro group of the latter compound was reduced to an amino group. The amino group was tosylated. The product thus obtained was nitrated to 4-nitro-3-chloro-2-methoxy-N-tosylaniline, which was methylated, saponified, and benzylated. From the 4-N-methyl-N-benzylamino-3-methoxy-2-chloronitrobenzene thus prepared, the diazonium chlorostannate was obtained in the usual way by reduction and diazotization.

EXAMPLE II White base paper for the diazotype process, of weight g./m. is sensitized with a solution containing 4-N-methyl-N-cyclohexylamino 3-methoxy-2-chlorobenzene, diazonium chloride, stannic chloride double salt g 30 Tartaric acid g 5 Aqueous polyvinyl acetate dispersion (Vinnapas H. 60) ml 30 in 1000 ml. of water and dried.

The one-component diazotype material thus obtained contains approximately 0.45 millimol of diazonium compound per square metre of the sensitized surface. A sheet of this material is imagewise exposed underneath a pencil drawing on tracing paper until underneath the imagefree portions of the drawing the diazonium compound has largely bleached out, after which the sheet is developed with developer C.

The copy shows a sepia-brown image on a foggy brown background.

If the above-mentioned sensitizing liquid contains, instead of the said compound, an equivalent quantity of the corresponding diazonium compound with a 6-chloro substituent, the diazotype paper thus obtained bleaches out less white, and gives copies which show stronger yellowing when exposed to daylight and show a less attractive brown azo-dyestufi image.

The diazonium compound used in this example was prepared as follows:

3-chloro-2 methoxy-N-methylaniline was cyclohexylated and then nitrated. From the 4-nitro-3-chloro-2-meth- 7 oxy-N-methyl-N-cyclohexylaniline thus prepared, the diazonium salt was obtained in the usual way by reduction and diazotization.

EXAMPLE III White paper of weight 150 g./m. coated on One side with a cellulose acetate film layer (approximately 50% by weight of combined acetic acid) of a thickness of approximately microns, which layer has been affixed to the paper by means of an adhesive and has been deacylated to a depth of about 4 microns to an acetyl con tent, calculated as combined acetic acid, of approximately by weight (which corresponds to an average number of acyl groups per glucose unit of the cellulose acetate of 0.7), is impregnated on the de-acylated side of the cellulose acetate layer with the following solution:

4 N methyl-N-benzylamino-3-n-butoxy-2 chlorobenzene diazonium chloride, zinc chloride double The diazotype material thus obtained is very lightsensitive. A sheet of this material is imagewise exposed underneath a transparent ink drawing until the diazonium compound underneath the image-free portions of the drawing has completely bleached out, and is then developed with developer A.

The copy shows a black image on a bright white background.

The diazonium compound used in this example was prepared as follows:

2,3-dichloronitrobenzene was converted into 3-chloro- 2-n-butoxynitrobenzene. The nitro group was reduced to an amino group, which was subsequently tosylated. The product thus obtained was nitrated, methylated, and saponified to 4-nitro-3-chloro-2-n-butoxy-N methylaniline. This compound was benzylated. From the 4-nitro-3- chloro-2-n-butoxy-N-methyl-N benzylaniline, the diazonium salt was obtained in the usual way by reduction and diazotization.

The present invention is not to be considered restricted to particulars of any of the compounds, materials or examples hereinabove described except as may be required by a fair construction of the appended claims, for various modifications and substitutions of equivalent nature will become available to those skilled in the art upon consideration of the nature of this invention.

What is claimed is:

1. A diazonium compound of the general formula,

wherein X is an anion,

Y is a halogen atom,

R is a non-branched, branched or lower alkoxy-substituted lower alkyl group, or an allyl, cyclohexyl, cyclopentyl or benzyl group,

R is a non-branched, branched or hydroxyor chloroalkyl group having at most 4 carbon atoms or a benzyl group, and

R is a cyclohexyl, methyl cyclohexyl, methyl napthyl,

benzyl or chloro-benzyl group.

2. A diazonium compound according to claim 1, where- Y is a chlorine or bromine atom,

R is an alkyl group having at most 4 C atoms,

R is an alkyl group having at most 3 C atoms, and

R is a cyclohexyl group.

3. A diazonium compound according to claim 1, namely, a 4-N-alkyl-N-benzylamino-3-alkoxy-2-chlorobenzene diazonium compound.

4. A diazonium compound according to claim 1, namely, a 4 N alkyl-N-cyclohexylamino-3-alkoxy-2 chlorobenzene diazonium compound.

5. A diazonium compound according to claim 1, namely, a 4 N alkyl-N-cyclohexylamino-3-alkoxy-2- bromobenzene diazonium compound.

6. A diazonium compound according to claim 1, namely, a 4 N methyl-N-benzylamino-3methoxy-2- chlorobenzene diazonium compound.

7. A diazonium compound according to claim 1, namely, a 4 N methyl-N-cyclohexylamino-3-methoxy- 2-chlorobenzene diazonium compound.

8. A diazonium compound according to claim 1, namely, a 4 N methyl N benzylamino-3-butoxy-2- chlorobenzene diazonium compound.

9. A diazotype material comprising a support carrying a light-sensitive layer containing a diazonium compound as defined in claim 1.

10. A one-component diazotype material comprising a support carrying a light-sensitive layer containing, in the substantial absence of an azo coupling component, a diazonium compound as defined in claim 2.

Referenos Cited UNITED STATES PATENTS 3,169,869 2/1965 Hendrickx et al. 9691 3,290,150 12/1966 Eenshuistra et al. 96-91 X-R FOREIGN PATENTS 6,407,303 1/1965 Netherlands.

NORMAN G. TORCHIN, Primary Examiner.

C. BOWERS, Assistant Examiner.

US. Cl. X.R. 

